In places where bodies of water at least partially freeze over during certain times of the year, there is often a need to travel across the frozen water. In some cases, this may be for emergency situations, such as where someone has fallen through the ice and must be reached for rescue. In others, it may be that one's home is on an island in the middle of a frozen lake. A snowmobile can be used to travel over solid ice, but it is rare that one can traverse a frozen body of water with complete confidence that the entire body of water is consistently solidly frozen. The rider, therefore, takes the risk that the snowmobile and rider may fall through thin ice at any time. A boat, on the other hand, may be able to move through water and break through thin ice, but will have little utility on solid ice. Therefore, there is a need for a vehicle that allows a rider to travel both over water and over solid ice.
Some progress has been made toward the development of such a vehicle and a number of patents disclose the conversion of conventional snowmobiles into aquatic vehicles. For example, U.S. Pat. No. 3,521,595 discloses the conversion of a conventional snowmobile into an aquatic vehicle for travel on water. This conversion involves the replacement of the steerable ground engaging snow skis with a buoyant supporting and steering arrangement that includes pontoons attached to the snowmobile body in the mounting arrangement coupled to the steering linkage of the snowmobile. The pontoons are disposed relative to the engine driven endless cleat track extending lengthwise under the body such that the track functions in the water as the propulsion means. Although this invention discloses the conversion of a snowmobile into an aquatic vehicle, it has significant disadvantages. First, the invention requires the removal of the snow skis in favor of pontoons. Such removal may be difficult and may make it difficult or impossible to replace the snow skis so that the snowmobile may eventually be used as an ordinary snowmobile again. Moreover, once converted, the only seating and storage space on the aquatic vehicle is on the snowmobile, which could make rescue operations difficult. Most importantly, the rudder used to steer this vehicle extends below the bottom surface of the pontoons, which prevents the vehicle from effectively travelling on snow and ice once it has been converted.
U.S. Pat. No. 4,893,692 discloses a floatable snowmobile made up of a one-piece molded plastic body. The body includes a rigid skin forming a shell defining an enclosed cavity in which there is provided an expanded closed-cell foam core of water-buoyant material. Floating skis are constructed as pontoons of similar construction to the body and replace the conventional snowmobile skis such that the whole snowmobile can float with a portion thereof out of the water so as to support a rider clear of the water in the event the snowmobile falls through ice. Although this invention also discloses a snowmobile that will not sink, it also has its disadvantages. Given its floatable construction, it is not as maneuverable as a standard snowmobile and requires significant modification in order to be converted back into a conventional snowmobile. Like the invention disclosed in U.S. Pat. No. 3,521,595, there is no seating or storage on the vehicle other than the seating and storage provided by the snowmobile, which could make rescue operations difficult. Further, and more importantly, there is no ability to effectively steer the vehicle when it is submerged in water.
Finally, U.S. Pat. No. 6,595,812 discloses an amphibious vehicle for traversing a body of water or solid terrain, such as a layer of ice floating atop a body of water. The vehicle includes a floatable boat hull having an elongate aperture therethrough, and a snowmobile for traveling over the solid terrain received in the opening and sealed in water impervious relation to the hull. The snowmobile includes an endless drive track, which supports the hull in spaced relation when travelling over solid terrain being and which rearwardly propels water to forwardly propel the vehicle through the water. A pair of skis supports the front of the hull in spaced relation with the solid terrain being traversed and each ski includes upturned forward ends mounting upstanding rudders for steering the vehicle as it traverses a body of water. The hull includes upwardly extending, downwardly opening pockets for receiving the front upturned ends of the skis and stabilizing arms, which are coupled between the frame and the skis. Upwardly inclined guides are provided on the underside of the hull for upwardly guiding the skis out of the water onto the ice floating on the water as the vehicle exits the water and moves onto the ice.
Although this vehicle has more room for storage and seating, it too has significant disadvantages. First, although the upstanding rudders allow the boat to be effectively steered once it is in water, the use of these specialized skis requires the original snowmobile skis to be removed and replaced. Second, the hard rowboat-like sides of the hull make it difficult for rescue people to lift people to be rescued into the craft, and could easily result in swamping or sinking of the vehicle. Third, the design of the bow is susceptible to a buildup of ice and snow, which could make it difficult for the craft to move up and out of the water and onto solid ice. Finally, this vehicle is solely an amphibious vehicle, which cannot be separated into a snowmobile and a boat.
Therefore there is a need for an amphibious vehicle that has sufficient seating and storage for rescue operations; that may be separated into an operational snowmobile and an operational boat; that is steerable both on ice and in water; that is designed to easily haul passengers from the water onto the vehicle; that does not require the removal and replacement of the snowmobile's skis in order for it to be effectively operated; and that has a hull that is not susceptible to ice and snow buildup.